Static Stiffness Index (SSI)
CircAid Medical Products designs and technologies parallel the proven principles of bandaging.
Subbandage pressures have been shown to be indirectly proportional to the strength length of the bandage when measured in the standing and laying down positions1-6. This difference in pressure resulting from posture change when measured in the gaiter area (8cm above the ankle-bone) is referred to as the Static Stiffness Index (SSI)4 and is a useful parameter to characterize in vivo stiffness for all forms of compression badages8.
This means when standing, non-elastic systems will produce higher pressures than elastic systems2,4,7. The higher the Static Stiffness Index, the more inelastic the system will be, and the lower the value the more elastic the system will be. Based on published pressure measurements, any Static Stiffness Index above 10 mmHg has been proposed to be considered inelastic, and anything below this value to be considered elastic2,5,7. All of CircAid Medical Compression Products are inelastic.
The benefits of a higher Static Stiffness Index are higher working pressures, lower resting pressures, and a contained limb volume that will not be allowed to swell further. However, because the legging will be very non-elastic and will produce low resting pressures it may slide if it is not adjusted when limb volume is lost or if it does not have structure to keep it in place such as a neoprene spine, shell, or foam liner.
If the Static Stiffness Index is slightly lowered the benefits of the completely non-elastic legging remain present, but resting pressures slowly become higher. This means that the legging will hug the limb more, may need to be adjusted less, and may show less signs of sliding than the more non-elastic garment. It may also contour unique limb shapes more efficiently due to a more pliable material.
What makes CircAid Medical Products so therapeutic are our high working (when standing, walking , or active) and low resting (when laying down or with limb elevated) pressures created by our non-elastic technology. The Static Stiffness Index value has been provided* for our daytime lower leg garments as a reference for you, your therapist, or your physician to help choose the appropriate CircAid product for your needs.
-CircAid Medical Products.
The Right Product. The Right Patient. The Right Reason.*Static Stiffness Indices were obtained by taking pressure measurements in the gaiter area under the CircAid leggings while supine and standing after applying the bands to 40 mmHg of compression in the seated position. For example, the T-3 EZ was applied with the bands tightened to give 40 mmHg while seated. When standing the pressure in the gaiter area increased to 58mmHg, and when laying down the pressure reduced to 23mmHg. The resulting SSI for this trial would be 35 mmHg (58 mmHg-23 mmHg = 35mmHg). Your results may vary and the SSI is provided for reference only.
1Thomas S, Fram P. An evaluation of a new type of compression bandaging system 2003. Available from: http://www.worldwidewounds.com
2Partsch H. The use of pressure change on standing as a surrogate measure of the stifness of a compression bandage. Eur J Vasc Endovasc Surg 2005;30:415-21
3Lee AJ, Dale JJ, Ruckley CV, et al. Compression therapy: effects of posture and application techniques on initial pressures delivered by bandages of different physical properties. Eur J Vasc Endovasc Surg 2006;31:542-52.
4Partsch H, Clark M, Bassez S, et al. Measurement of lower legcompression in vivo: reccomendations for the performance of measurements of interface pressure and stifness. Dermatol Surg 2006; 32:229-38.
5Hafner J, Botonakis I, Burg G. A comparison of multi-layer bandage systems during rest, excercise, and over 2 days of wear time. Arch Dermatol 2000;136:857-63.
6Barbenel JC, Sockalingham S, Queen D. In vivo and laboratory evaluation of elastic bandages. Care Sci Pract 1990;8:75-9.
7Mosti G, Mattaliano V. Simultaneous changes of leg circumference and interface pressure under different compression bandages. Eur J Vasc Endovasc Surg 2007;33:476-82.
8Partsch H, Clark M, Mosti G, et al. Classification of compression bandages: Practical aspects. Dermatol Surg 2008; 34(5):600-609